The Buzz...

Thank u for ur comment gameo
So let's talk about this deck, first of all is very hard to list all the right cards and play with only 40 slots available (if u play more than 40 cards the deck doesn't work taht good).
As u can see Trickster is a 3 copy card, that's because she open 5 card and add all GW, all Worldswalker spirits, plus Isis' power and Isis' Temple, then it can also set ur bottom deck as u like which is very key in ur matches. My list didn't really need to see ultimate, you need to see all card to setup you "2 atk step end game". because of this u have to see all ur nexus and Ramdiel
Ophanimon can advent on all cost 5 or more yellow spirit, as u can read, you also can advent him on Nefiel of course, but usually u advent on Ramdiel, Trickstar or Mehetel+Sirius
Ophanimon is probably the second most power full card of the deck, it can make u do the -4 life combo.
Then let's talk about the 1 copy of Gaianohoko, I was thinking about removing it because it isn't really that grate I use it in very few cases and of course it doesn't work on Alex, but sometimes u can do Isis' Power+Nefiel+Gaianohoko and have a perfect block on atks.
Miridiel is a great card to have only in late game, u always want to advent Ophanimon not her; she can obviously save u with the +3 life block/atk but if u find ur self atking with her, u rn't in a good spot at all (she's kinda of "last resort").
Now as far as Sirius is concerned is worth mentioning that I wasn't playing (I played the second Gaianohoko), maybe I will change it, but sometimes I really feel good with that +3 cost and +1 core which comes real handy with ur flash step.
U really need to test yellow lot of times before understanding all of my over viewing and all combos , but I ensure u: this is the greatest list u can play at the moment, u haven't any bad match up at all and no one is actually playing hand-control cards

Trickster cant add any of the Ultimate's
Ophanimon can only advent to the "Ultimate" family from the Digimon sets, not Ultimate's
why only 1 Gaiahonoko?
why only 1 Miridiel? its a great card to have
Sirius isnt really that good

Interesting combination... I assume the idea is to use the Cell Medals and Birth Day to dig for your key cards.
My one question is why you don't have the actual Kamen Rider Birth in here, seeing as he gets you Cell Medals from the top of your deck, and his LV2 effect makes the draw effect of Cell Medals free once per turn.

This is good but I would suggest u add cards like Omnimon Merciful Mode and Alphamon to help u. Evil Cherubimon is also nice. Maybe also add some more defensive magic like Delta Barrier. Just suggestion.

Magic-centred deck is rare these days with overflowing grandwalker decks, good to see one! Although I am not a professional yellow player, I think maybe you can consider the following changes to modify the deck, as to tackle with the relatively weak defense problem of magic decks and strengthen the overall combo:

1) Just as a reminder, "Magic Book" is limited

2) Highly recommend the magic-centred nexus : Yellow Holy Relic

3) Highly recommend "the chosen searcher alex" as a standard defense card these days which does not fear burst discard and give you draws or resources.

4) Consider focusing on one to two families as it is now a bit difficult to do advents and support mutually with the diverted families (e.g. focus on divine spirits

You can remove imperialdramon and add 1 alex and add 1 death taurus cause it will help you to both defend and atk to confuse the opponent with 2 types of burst and you can draw easily.this will make the opponent to get confused about which card is the burst and can make blunder,so i will suggest to do like this

The build is pretty good the the tempo is fast. But instead of mercury blade, I would suggest putting in the cost 2 brave that treat seadra as highest level.

Reasons are:
1. Seadra alone with its effect can deal three damage, and with one or two attacks from your minions, it is deadly enough.

2. Though Seadra is having high bp, it is vulnerable against trigger counters or any spell that remove it from field (especially red spells that destroy ultimates with two or more symbols) , unless it reaches level 5, which requires 9 cores.

3. Spell sealing also counters any spell like burst wall, diamond wall or limited barrier, enusring your opponent do not get another turn.

You may say 9 cores is not too much but putting them all on seadra is risky and inefficient in my opinion, so the cost 2 brave really a nice choice, not to say it also get spirit soul:blue. If you are putting in other ultimates, they can also benefit from it, especially low cost ones.

Apart from the brave, you may consider putting in zero counters, as no cost summon is pretty annoying these days, also the last blue x rare from BS44, to counter nova.